Resources
Unit Conversion Sites
Yokogawa HART and BRAIN Pocket Guides
Control Valve Sizing Program
Safety Relief Valve Sizing Program
Digital Yewflo Vortex Flow Meter Sizing Program
ANSI Pressure Ratings
Yokogawa General Specification Data Sheets
Valve Seat Leakage Chart The Fluids Control Institute (FCI) Standard ANSI/FCI 70.2 establishes a Valve’s allowable seat Leakage Rate. The standard recognizes five degrees of seat tightness.
Maximum Seat Leakage
Test Fluid
Test Pressure
Relative Seat Tightness
Class II
0.5% of rated CV
Water
45 to 60 PSI
1.0
Class III
0.1% of rated CV
5.0
Class IV
0.01% of rated CV
50
Class IV+
0.0015 ml /min/inch of trim size/ ΔP(PSI)
Max Operating ΔP
150,000
Class V
0.0005 ml /min/inch of trim size/ ΔP(PSI)
300,000
Class VI
about 0.9 ml/min ∗
Air
50 PSI
600,000
